Not possible to ADD SCENE at all - Video Editor
First of all, make different scenes, each one with their animation.
Then make a new scene without any animation and open the Video Editing tab.
Finally, from the Video Editing tab, try to add a scene either by Shift+A with the mouse hovering on the Video Sequencer panel, or as you did, by clicking on the Add&gt;Scene dropdown menu.
You should be able to find all scenes but the new one you're video editing from!